Concrete Floors — Cement Association of Canada

Concrete Floors - Cement Association of Canada

Concrete Floors

Housing Information — (Floors)

Floors: Concrete is a natural choice for floors in homes with ICF or concrete block walls. In addition to delivering benefits similar to the walls — resistance to natural forces (wind, rot and insects), sound reduction, and improved thermal performance — concrete floors are long-spanning, squeakless and can accommodate efficient, comfortable radiant heat systems.

Floors fall into four categories:

composite/steel joist concrete/steel deck concrete joists precast

Composite Concrete/Steel Joists

Light steel joists supporting concrete on a steel deck or ribbed steel pan are widely available. Typical spans =4.5 to 9.0 m or longer using 200 — 610 mm joists plus 40 — 100 mm concrete.

Hambro a proprietary system, uses sheets of plywood temporarily held between joists with removable roll bars. Steel mesh is draped over the joist, then topped with concrete, bonding it to the top chord and creating a reinforced composite deck. The plywood and roll bars can be reused. Because of the composite action between joists and concrete, this system is somewhat lighter than plain joists/steel deck combinations.

C-Floor is another unique composite system which uses cold formed C-sections at 600 to 750 mm o.c. instead of steel joists. The 200 to 250 mm deep C-sections support a 75 mm concrete slab on ribbed steel pan. Composite action is created by continuous bond bars secured to the top of the C-sections by patented shear transfer devices. Typical spans 5.5m to 7.9m support live loads up to 4.8 KPa.

Concrete/Steel Deck

Metal deck made from plain or galvanized steel sheet rolled into ribbed profiles can be used to form concrete floor slabs. Steel deck can be used strictly as a form for the concrete deck slab or it can be used as part of a composite design where deck and concrete act together structurally. For house construction, 18 — 24 ga. (1.2 — 0.6 mm) sheets with 38 — 76 mm deep ribs is used.

When the decking is used solely as a form, steel reinforcing rods and concrete are designed to carry all loads. Two examples that have been tested for fire and sound performance are shown below:

Temporary supports installed under the deck at 1.5m before the pour must remain in place until the concrete reaches 80 percent of its design strength.

For a composite concrete/steel deck floor, a similar steel deck with dimples formed into the vertical flutes to create a physical bond with the concrete is used. This results in very efficient use of both materials. A 22 ga (0.75 mm) 75 mm composite deck with 75mm of 25 MPa concrete on top — total thickness 150 mm — can span up to 4.5m with no reinforcement. Temporary supports at 2.25m are required until the concrete develops sufficient strength. For design, either the ASCE Standard Specification for Design of Composite Slabs or the SDI Composite Deck Design Handbook should be followed. In Canada CSSBI S3-88 Criteria for the Design of Composite Slabs prepared by the Canadian Sheet Steel Building Institute or the Cement Association of Canada Concrete Housing Handbook could be used.

Concrete Joist

There are several systems available for casting concrete joist floors. Some use removable metal or fiberglass forms. Others use stay in place composite steel or plastic forms. Typical systems produce 200 mm deep ribs 600 — 900 mm on centre. With 50 — 75 mm thick topping, total floor thickness is 250 — 300 mm. One reinforcing bar is placed near the bottom of each rib and most systems require welded wire mesh in the top slab. For joist floors using composite steel forms, spans of 4.8 — 8.0m are common. Bulkheads to retain the concrete between the ribs where they meet a wall are provided as part of the forming system. Composite steel forms that stay in place are available from Canadian Steel Inc.

A method of forming concrete joist floors using foam forms is now making its way to North America from Europe where it has been used for several years. Hollow core foam planks, shaped to form concrete ribs at 460 — 760 mm centres, stay in place after temporary bracing is removed. Attachments for ceiling finishes can be incorporated into the foam floor forms.

Precast

Precast prestressed hollow core concrete slabs or planks for housing are usually 1220 mm wide and 150 mm or 200 mm thick. Although designs and widths vary somewhat, they normally have evenly spaced voids running the length of the slab with prestressing tendons in between. Hollow core is machine-extruded in long continuous beds and cut into planks to final dimensions at the plant. They may be cut to customized widths or shapes and reinforced for stair openings and other speciality applications. Holes for services may be cut on site if necessary. Hollow core slabs are set on ICF walls by crane and anchored with bent reinforcing bars set into the shear key joint between planks. The joints are then grouted to complete the installation.

Precast products have constant depth with a relatively flat top surface and a very smooth underside that can be exposed as a ceiling with a minimum of additional treatment. Carpet and underpad can be laid on top with a minimum of finishing and levelling. A thin cement/latex grout or a concrete topping is required under linoleum or other thin floor finishes. A 38mm concrete topping is applied where radiant heat is to be installed.

Systems that employ small concrete T joists with light autoclaved cellular panels set between them to support a cast-in-place floor slab have been used for many years in other parts of the world. As the use of concrete in low rise housing in North America intensifies, this and other concrete floor systems will likely find their way into the marketplace.

Concrete Floors

Housing Information — (Floors)

Floors: Concrete is a natural choice for floors in homes with ICF or concrete block walls. In addition to delivering benefits similar to the walls — resistance to natural forces (wind, rot and insects), sound reduction, and improved thermal performance — concrete floors are long-spanning, squeakless and can accommodate efficient, comfortable radiant heat systems.

Floors fall into four categories:

composite/steel joist concrete/steel deck concrete joists precast

Composite Concrete/Steel Joists

Light steel joists supporting concrete on a steel deck or ribbed steel pan are widely available. Typical spans =4.5 to 9.0 m or longer using 200 — 610 mm joists plus 40 — 100 mm concrete.

Concrete Floors - Cement Association of Canada

Hambro a proprietary system, uses sheets of plywood temporarily held between joists with removable roll bars. Steel mesh is draped over the joist, then topped with concrete, bonding it to the top chord and creating a reinforced composite deck. The plywood and roll bars can be reused. Because of the composite action between joists and concrete, this system is somewhat lighter than plain joists/steel deck combinations.

C-Floor is another unique composite system which uses cold formed C-sections at 600 to 750 mm o.c. instead of steel joists. The 200 to 250 mm deep C-sections support a 75 mm concrete slab on ribbed steel pan. Composite action is created by continuous bond bars secured to the top of the C-sections by patented shear transfer devices. Typical spans 5.5m to 7.9m support live loads up to 4.8 KPa.

Concrete/Steel Deck

Metal deck made from plain or galvanized steel sheet rolled into ribbed profiles can be used to form concrete floor slabs. Steel deck can be used strictly as a form for the concrete deck slab or it can be used as part of a composite design where deck and concrete act together structurally. For house construction, 18 — 24 ga. (1.2 — 0.6 mm) sheets with 38 — 76 mm deep ribs is used.

When the decking is used solely as a form, steel reinforcing rods and concrete are designed to carry all loads. Two examples that have been tested for fire and sound performance are shown below:

Temporary supports installed under the deck at 1.5m before the pour must remain in place until the concrete reaches 80 percent of its design strength.

For a composite concrete/steel deck floor, a similar steel deck with dimples formed into the vertical flutes to create a physical bond with the concrete is used. This results in very efficient use of both materials. A 22 ga (0.75 mm) 75 mm composite deck with 75mm of 25 MPa concrete on top — total thickness 150 mm — can span up to 4.5m with no reinforcement. Temporary supports at 2.25m are required until the concrete develops sufficient strength. For design, either the ASCE Standard Specification for Design of Composite Slabs or the SDI Composite Deck Design Handbook should be followed. In Canada CSSBI S3-88 Criteria for the Design of Composite Slabs prepared by the Canadian Sheet Steel Building Institute or the Cement Association of Canada Concrete Housing Handbook could be used.

Concrete Joist

There are several systems available for casting concrete joist floors. Some use removable metal or fiberglass forms. Others use stay in place composite steel or plastic forms. Typical systems produce 200 mm deep ribs 600 — 900 mm on centre. With 50 — 75 mm thick topping, total floor thickness is 250 — 300 mm. One reinforcing bar is placed near the bottom of each rib and most systems require welded wire mesh in the top slab. For joist floors using composite steel forms, spans of 4.8 — 8.0m are common. Bulkheads to retain the concrete between the ribs where they meet a wall are provided as part of the forming system. Composite steel forms that stay in place are available from Canadian Steel Inc.

A method of forming concrete joist floors using foam forms is now making its way to North America from Europe where it has been used for several years. Hollow core foam planks, shaped to form concrete ribs at 460 — 760 mm centres, stay in place after temporary bracing is removed. Attachments for ceiling finishes can be incorporated into the foam floor forms.

Precast

Precast prestressed hollow core concrete slabs or planks for housing are usually 1220 mm wide and 150 mm or 200 mm thick. Although designs and widths vary somewhat, they normally have evenly spaced voids running the length of the slab with prestressing tendons in between. Hollow core is machine-extruded in long continuous beds and cut into planks to final dimensions at the plant. They may be cut to customized widths or shapes and reinforced for stair openings and other speciality applications. Holes for services may be cut on site if necessary. Hollow core slabs are set on ICF walls by crane and anchored with bent reinforcing bars set into the shear key joint between planks. The joints are then grouted to complete the installation.

Precast products have constant depth with a relatively flat top surface and a very smooth underside that can be exposed as a ceiling with a minimum of additional treatment. Carpet and underpad can be laid on top with a minimum of finishing and levelling. A thin cement/latex grout or a concrete topping is required under linoleum or other thin floor finishes. A 38mm concrete topping is applied where radiant heat is to be installed.

Systems that employ small concrete T joists with light autoclaved cellular panels set between them to support a cast-in-place floor slab have been used for many years in other parts of the world. As the use of concrete in low rise housing in North America intensifies, this and other concrete floor systems will likely find their way into the marketplace.


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